Method and apparatus for the electrodeposition of metal



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METHOD AND APPARATUS FOR THE ELECTRODEPOSITION OF METAL Filed Deo. 50, 1932 lO Sheets-Sheet I5 l 1 lo IO l INVENTOR March 30, 1 937.

F. L. ANTlsl-:LL 2,075,331

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METHOD AND APPARATUS FOR THE ELECTRODBPOSITION OF METAL Filed Deo. 30, l0 Sheets-Sheet 6 INVENTOR PMAM March 30, 1937. F. 1 ANTISELL l2,075,331 R 'THE ELECTRODEPOSITION OF MEnTAL h METHOD AND .APPARATUS FO 10 Sheecs-SmaefI 8 Filed Deo. BO, 1932 L JMO" A l 225 wzg/ 4 F7513 I Il?? VIII/IIIA INVENTOR' A @www March 30, 1937. F. L.. ANTISELL METHOD AND APPARATUS FOR THE ELECTRODEFOSITION OF METAL v1o sheets-sheet 9 AIAA INVEN'roR hun n" Filed Dec. 30, 1952 k March 30, 1937. F. L'. ANTlsx-:LL 2,075,331

METHOD AND PPARATS FOR THE ,ELECTRODEPOSITION OF MIETAL Filed Dec. so, 1932 1o sheets-sheet 1o SE'ZZ.

'INVEN'roR FAMA LW Patented Mar. 30, 1937 PTET FFICE METHOD AND APPARATUS FOR THE ELEC- TRODEPOSITION OF METAL Frank L. Antisell, Wilknsburg, Pa., assigner to Copperweld Steel Company, Glassport, Pa., a corporation of Pennsylvania Application December 30, 1932, Serial No. 649,532

20 Claims.

This invention relates generally to a method and apparatus for the electrodeposition of metal, and more particularly to such method and ap- .paratus for electrodepositing metal on a core in vorder to produce a bmetallic article. The inv ention is particularly described herein as ap- .plied to the manufacture of bimetallic articles .having a ferrous core or base and a coppery coating. Such products supply a large demand in Wire, cable, strips, tubes, and the like. They are of great value in that the ferrous core, such as steel, supplies strength and the copper provides .electrical conductivity and resistance to corrosion. The invention is applicable, however, to

f the production of other combinations of metals.

A non-ferrous base or core may be coated with copper, nickel or other metal. For trolley wires, a copper core may be coated with iron. Bimetallicf articles may be made by depositing nickel or other metal on a core of copper or other metal. The present application is a continuation-in- -part of my copending application Serial No.

359,624, filed May 1, 1929.

It has been proposed heretofore to make bimetallic articles in various Ways. Attempts have been made to weld previously formed copper to a vsteel core, but these attempts have not been entirely successful. The most satisfactory method in use consists in applying the copper in a -molten state to the core or base. The core is suitably cleaned and fluxed, and While centered in a heated mold, molten copper is poured around it. The ingot formed in this way is rolled to the desired shapes. The ratio of copper to steel in the ingot is governed by the relative size of the mold and steel core.

The requirements of the trade are such that in wire, for example, various ratios of crosssectional area of copper to steel must be furnished. Some wires may have only 5% copper; others may have as high as 40% to 50%. Unfortunately, these requirements, as Well as other requirements as to the purity of the copper and the concentricity of the steel core with the copper jacket, introduce a large number of manu- -facturing problems. Where the copper shell is thick, the diliiculties of rolling are increased, be-

-causc the copper, being softer and more easily `deformed than the steel, tends to flow between the rolls more easily than the steel. It is therefore, difficult to maintain the concentricity of the' steel and the copper. Another great diiculty arises in the pouring of the ingot. If the r.copperis too hot, a certain amount of steel dissolves into the copper and reduces its purity,

thuslowering the electrical properties of the product. If the pouring is carried out at too low a temperature, the permanent Weld, which is the great virtue of the process, is not obtained.

f- In accordance with the preferred embodiment of this invention, a core is passed through a single electrolytic bath or a series of electrolytic baths and metal is deposited thereon. The core is passed through the baths under high tension and it is rotated about its axis as it is fed through the bath. The tension maintains the core straight, produces a better deposit than can be obtained otherwise, and the rotation of the core about its axis insures an even deposit of metal on all sides of it. The core is .fed from a. pay-reel and passes through a series of cleaning baths, after which it passes through a series of electrodepositing baths. It is then wound up on a take-up reel. Both the pay-reel and the take-up reel are mounted in frames which are rotatable at substantially a right angleto the axes of rotation of the reels, so that the core is rotated about its axis as it passes through the baths. The anode used in the principal electrodepositing solutions preferably is a moving Wire, hereinafter termed a drag wire. This drag wire is fed from a reel, and after passing through the electrodepositing solutions, is Wound up on another reel. It moves through the baths alongside of the core which forms the cathode and the metal is deposited from the drag wire onto the core. Other types of anode may, however, be used instead of the moving drag Wire. I may use stationary anodes such as slabs of the metal to be deposited, or metallic shot, or I may use an insoluble anode and add the metal to be deposited as a salt or as metal to the electrolyte.

In the accompanying drawings, which illustrate the present preferred embodiment of my invention and also certain modications,

Figure 1 is a diagrammatic plan View of the whole apparatus, the View being shown in sections for convenience of illustration;

Figure 2 is a side elevation of a number of the containers or tronnels which contain the various solutions through which the core passes, and illustrates the means for iiltering and recirculating the solutions. By tronnel I mean a trough-like structure with open ends in which the electrodeposition takes place, the electrolyte being supplied thereto at such rate as to maintain the desired quantity of electrolyte therein.

Figure 3 is a plan View of the mechanism at the entrance end of the apparatus for supplying the core to the baths, and shows the .pay-reel and the frame in which it is mounted;

Figure 4 is a side elevation of the mechanism shown in Figure 3;

Figure 5 is a sectional View of the snubber wheel and brake mechanism which is mounted in the same frame as the payfreel located at the entrance end of the apparatus; u

Figure 6 is a transverse section on the line VI-VI of Figure 3, illustrating the means for mounting the pay-reel and take-up reel in their frames;

Figure '7 is a side elevation of the take-up reel and its driving connections;

Figure 8 is a plan view of the apparatus shown in Figure 7 Figure 9 is a section on the line IX-IX of Figure 7, illustrating a clamping means for preventing release of tension on the core;

Figures 10 and ll are, respectively, a side elevation and a plan view of roller cathodecontacts located between the tronnels which hold the electrodepositing solutions;

Figure 12 is a view, partly in section and partly in elevation, of one of the steam nozzles arranged between certain of the tronnels near the entrance end of the apparatus for cleaning the core;

Figures 13 and 14 are, respectively, a sectional View and an elevation of a high current density circular anode used to prevent re-solution of a previously deposited metal;

Figure 15 is a sectional view through one of the tronnels illustrating the contact for the anode or drag wire;

Figure 16 is a plan View of a driven roller cathode contact located within one of the tronnels;

Figure 17 is a sectional View on the line XVII- XVII of Figure 16;

Figure 18 is a wiring diagram showing the electrical connections for a number of the tronnels which contain the various baths;

Figure 19 is a plan view, and Figure 20 is a section on the line XX-XX of Figure 19, of a means for shielding the cathode contacts in order to equalize the current density along the cathode;

Figures 21, 22 and 23 are, respectively, a plan View, a side elevation, and a section on the line XXIII-XXII of Figure 21 illustrating a preferred type of rollers for supporting the core and compacting and refining the grain structure of the deposited metal, and

Figure 24 is an enlarged View of a portion of the core having deposited metal thereon and illustrating the manner in which the rollers shown in Figures 2l, 22 and 23 compact and rene the deposited coating.

Referring more particularly to the accompanying drawings, and for the present to Figure 1, the core or wire to be coated with metal is fed from a pay-reel 2 through a series of cleaning baths 3, 4 and 5. The cleaning baths may be of different compositions, but I have found that in the coating of a steel core with copper, or rst with nickel or tin and thereafter with copper, eiective cleaning can be accomplished when the bath 3 is a soda solution, the bath 4 is a sulphuric acid solution, and the bath 5 is a nitric acid solution. The core 6 then passes through a solution of a nickel salt, for example nickel sulphate, in the tronnel 1, and after that passes through a copper solution in the tronnel 8, and thereafter through a plurality of tronnels 9, each of which contains an acid solution of a copper salt such as copper sulphate. The character of the grain structure of the electrolytic deposit of copper is materially affected by the temperature of the electrolyte. It is particularly important that the initial deposit of copper be ne grained, as the succeeding grain structure built on the initial deposit cannot be good if the initial deposit was poor. In other words, poor grain structure in the initial deposit carries through the superposed deposit. Accordingly, the temperature of the solution in the tronnel 8 is lower than the temperature of the solutions in the tronnels 9. the temperature of the former being about 70 F., while that of the latter is about F. After passing through the last of the tronnels 9, the core is wound up on a take-up reel II) which is rotatably mounted in a frame II driven by a motor and gearing I2 so as to rotate the frame at substantially a right angle to the axis of rotation of the reel I0. The pay-reel 2 at the entrance end of the apparatus is mounted in a similar framework I3 driven by a motor and gearing I4. The construction is such that the core rotates about its axis as it is advanced through the various baths.

The tronnels which contain the various solutions are U-shaped in cross-section, being open at the top and ends. The tronnels do not form closed containers for the baths, but on the contrary are open at their ends so that it is necessary to continuously circulate the solution through the tronnels in order to maintain a. desired level of the electrolyte therein. The so# lution in each tronnel ows out of the ends lof the tronnel, is collected, ltered if necessary, and then returned to the tronnel, As shown in Figure 2, the solution ows from the ends of each tronnel into receivers I5 and is conducted by pipes I6 to a sump I1. It is then circulated by a pump I8 through pipes I9 and 20 through a filter 2|, and then returned to the tronnel.

The solution in the sump I1 is heated by a steam i pipe 22 which is connected to a steam line 23. The use of such open end tronnels for the solutions eliminates the necessity of providing stuing boxes, which would be required with electrodepositing tanks of the usual closed end construction. 'I'he stuing boxes are objectionable for the reason that the packing scratches the surface of the deposited metal and may introduce foreign matter into the deposited metal. Also, by using a series of spaced tronnels instead of a single bath, different solutions can be used in the different tronnels, and these solutions can be filtered and recirculated back to the tronnels. It will be understood that when reference is made to open end tronnels, this does not mean that the ends are absolutely free of any structure impeding the flow of liquid. A weir or baflle may be employed, the essential thought being that the entrance and exit of the wire is effected without it passing through stuifing boxes or the like.

Located between the tronnels 3, 4 and 5, which contain different cleaning solutions, are steam nozzles 25 and water nozzles 26 connected by pipes 21 and 28, respectively, to a steam line 23 and a water line 29. The nozzles 25 and 26 subject the core between tronnels to jets of steam and water which, taken in conjunction with the various cleaning solutions, produce a very clean wire on which a good deposit of metal can be made. As shown in Figure 2, the stem jets 2 5 apply steam to the core wire 6 at an acute angle and in a direction opposite to the movement of the wire. It has been found that by so arranging the steam jets, the liquid on the Wire is forced backwardly so that the portion of the wire which passes the jet is substantially dry. Where a steam jet is applied at right angles to the direction of movement of the wire, it causes the liquid on the wire to splatter on both sides of the point Iof application of the jet and forms spots 'or stains on the wire. This objectionable spotting of the wire is overcome where the jets are applied as indicated so as to force back the liql0 uid 'on the wire in the opposite direction to that vin which the wire moves. Another steam jet 25 is also used between the tronnels 5 and 1 to further clean the core before it passes into the nickel solution in the tronnel 1. It is advan- 1'5 tageous in some cases to coat the core first with a 'deposit of another metal such as nickel or tin before applying the copper coating. Nickel, which is preferred, readily forms an alloy both with vthe steel core and with the copper coating. The `deposit-ion of copper on the core which has previously Abeen coated with nickel begins in tronnel 8 and is continued in tronnels 9. A copper drag wire -3I is unwound from a reel 32 and travels parallel to the core 6 through all of the.

tronnels 9 except the last one shown in Figure 1. The anodes in tronnel 8 and the last one of tronnels 9 are stationary, of any suitable type, as rods, casting, shot, etc. The drag wire 3| is I wound on a reel 33 located adjacent the exit end 4of -the apparatus. During the deposition process, the core 6 and the drag wire 3I both move through the depositing baths. In addition to this, the core which is maintained under great tension is also rotated about its own axis, so

35 that the deposition Will be uniform. The tension on the core is preferably from 20,000 to 50,000 pounds per sq. in., or approaching the yield point of the base material. The means for supplying the core to the baths is illustrated in Figures 3 to 6. The reel 2 is rotatably mounted in a frame I3, so that as the reel is rotated about its axis, the core unwinds from the reel. The frame I3 is rotatable about its longitudinal axis, which axis is at substan- -745 tially a right angle to the axis of the reel 2.

The frame is rotated through a driving connection I4. The pay-reel 2 and the take-up reel IU are similarly mounted for easy removal from the frames I3. As shown in Figure 6, the reel 50 2 is provided with hubs 34 which are secured in place by rods 35. The hubs are supported by cone-shaped bearing sleeves 36 which are internally threaded for reception of screws 31. The sleeves 36 are slidable within housings 38 secured 55 to the frame and are adjusted by rotation of the hand wheels 39. With this construction, it is an easy matter to remove an empty reel from the frame and insert a full reel.

'Ihe core or wire 6, after leaving the pay-reel 60 2, passes between rollers 40 and 4I and is then wound around a snubbing wheel 43 in a direction the reverse of that in which it was Wound around the ree1 2. The reverse winding of the core around the pay-reel and snubbing wheel 65 acts to straighten out the core before feeding it to the baths.

Means is provided for delivering the core from the snubbing wheel so that it will be in alinement with the guide rollers 44. For this purpose a wob- '70 r'bler ring 45 ts around the rim 46 of the snubbing wheel 43. The wobbler ring is provided with a notch 41, and into this notch fits a stud '48 which 'is screwed into the rim 46. Th'ere is a loose t between the ring 45 and the rim 4'6 and between the '75 notch 41 and the stud 48. As the wheel 43 rotates,

the wobbler ring 45 is carried with it due to t1 notch and stud connection 41, 48. 'Ihe ring caused to wobble by a wedge 49 and a guide 50 s cured to the frame. The guide 50 holds the wo bler ring close to the flange 5I at one side of tI snubbing wheel and the wedge 49 spreads the ri:

' away from the flange 5I at the other side of tI wheel. This arrangement delivers the core fro the snubbing wheel in alinement with the gui rolls 44.

It has been stated that the core is fed throug the baths under high tension. This tension is a coinplished by using a pulling means at the ei end -of the apparatus and providing the snubbli wheel with a brake. The brake comprises bloc 52 which press against the web 53 of the snubb wheel. Each of the blocks is made up of a layer of brake lining, a layer 55 of wood, and a layer of rubber. The rubber layer is secured to a met plate 51 into which is threaded a sleeve 58. Ear of the sleeves 58 is supported by a bearing 59 s cured by bolts 60 to the frame I3. The bra] blocks are pressed against the web of the snubb wheel by turning screws 6I having secured there heads 62 which t into the sleeves 58. The bra] provides any desired amount of back tension. 'Il tension feature is highly important to the ol taining of a satisfactory and uniform deposit.

'Ihe take-up reel I0 and its driving connectiol are illustrated in Figures 7 and 8. The reel rotatably mounted in the frame II in the san manner that the pay-reel 2 is mounted in i frame I 3. The frame I I is rotated about its long tudinal axis by the driving motor and gearing illustrated in Figure 1. The motors and drivir connections at the entrance and exit ends of 'tl apparatus are synchronized by suitable electric controls so as to rotate the core about its axis z the same speed at both ends of the apparatu The core 6, after passing through the last tronn 9, passes around a drum 10, then around a whe 1 I, and is then wound on the take-up reel I0. Tl take-up reel is driven from a motor 12 which mounted on the frame II and rotates therewit To the armature shaft 13 of the motor is secure a pinion 14 which meshes with a gear 15 secure to a shaft 16. The opposite end of the shaft l carries a pinion 11 which meshes with a gear l secured to a shaft `19. The opposite end of tk shaft 19 carries a pinion 80 which meshes with gear 8| which, in turn, meshes with a gear ring t secured to the take-up reel I0.

Spacing means is provided for guiding the co1 .wire as it is wound up on the reel I0. The co1 wire is guided between guide ngers 83 which fori a part of a traveling guide 84 which moves bac and forth across a screw 85 having a return threa cut therein. The screw 85 is rotated by means a sprocket wheel 86 secured thereto and connecte by a chain 81 to a sprocket 88 secured to the hu of the reel l0. A rod 89 ts into notches 9 formed in the lower ends of arms 9I of the guidl so as to prevent the guide from rotating with th screw.

The axles 92 of the frame II are mounted i bearings 93. The leftehand axle, as viewed i Figure 7, extends beyond the bearing for som distance and is provided with contact rings 9| These rings make contact with brushes 95 whic are connected by wires 96 to a source of electrl current. The motor 12 is connected to the ring 94 by wires 91 which extend through the axle 9i In the construction just described, the frame is ro tated about its longitudinal axis by the motor an driving connection I2, and the take-up -reel is ro tated so as to wind up the core wire by the motor 12 which is mounted on the frame and which rotates therewith. The frame may be rotated about its longitudinal axis and the take-up reel ro- 5 tated to wind up the wire by a single motor, but it is preferred to have separate motors and driving means for the frame and for the reel.

Figure 9 illustrates a device for preventing the release of tension on the coated core. It comprises a head 98 which, in the embodiment shown, is of truncated cone-shape secured to the axle 92 of the frame by screws 99. The head is provided with openings |00 arranged at an angle to each other and converging in a direction opposite to that in .15 which the core travels. A clamping jaw |0| is arranged in each of the openings, and a spring |02 disposed within each opening abuts against the end of each jaw 0 I tending to force them toward each other. When the core 6 moves to the right, as viewed in Figure 9, the springs are cornpressed and the jaws are forced into the openings and moved apart a distance suilcient to allow the core to move between the jaws. However, the core is prevented from moving to the left since in this direction the springs force th'e jaws together, so

that they grip the core. This arrangement prevents loss of tension on the core when a full takeup reel is removed and is replaced by an empty reel. I have found that in certain cases it is possible to provide sufficient frictional resistance in the working parts of the take-up reel that this resistance alone is suicient to keep the wire under tension when the motor is stopped.

Roller contacts arranged between the tronnels are employed for making the electrical contact with the core Wire 6 which forms a cathode in the process. These rollers are shown in Figures 10 and 11. A copper roller |03 is mounted in a bearing |04, and the bearing is secured to a strap |05 which is adjustably guided by rollers |06 secured to a plate |01, the plate being secured by screws |08 to a support |09. This manner of mounting enables the roller to move slightly in order that it may provide good contact with the core Wire 6. The roller |03 is rotatable on the lower end 0 of a pipe which extends upwardly beyond the support |08. The upper end of thev pipe is funnel-shaped so that liquid may be easily introduced through the pipe and 5 suppued to the roller. The lower end Hc of the pipe is perforated so that liquid supplied thereto leaks out and trickles down over the roller and onto the core wire 6. Slightly acidulated water is supplied through the pipe l to the roller. One part of sulphur-ic acid to one thousand parts of water may be used, and it has been found that in this manner the formation of a dark colored stain which otherwise would be formed on the core is prevented. The core is supported adjacent the roller |03 by a roller ||2 supported by a pipe H3, through which acidulated water may be sup plied to the roller in the manner just described. The axis of the roller |2 is arranged at an acute angle to the direction of travel of the core, thereby aiding in rotating the core as it is pulled over the roller.

Where the cathode contacts are immersed 1n the baths contained in the tronnels, there is a 70 tendency for nodules of copper to form on the contacts. The nodules scratch the metal deposited on the cathode, which causes entrapment of the liquid in the scratches, and this, in turn, produces planes of weakness in the deposited 75 metal. It is, therefore, of advantage to arrange driven roller arranged Within one of the tronnels.

The tendency of the metal of the bath to form nodules on the roller contact is eliminated by using a scraper which prevents the metal from adhering to the contact. With this arrangement,

the contact can be used in the bath instead of between baths without injuring the coating of the cathode. With this type of contact, a single long tronnel can be used in place of the plurality of spaced tronnels 9 shown in Figure 1. 'I'he employment of spaced baths has a tendency to4 form annular rings of deposited metal, the different rings having been formed while the core was passing through the different tronnels. Under conditions in which contacts can be immersed in the bath and the formation of nodules onthe contacts and scratching of the cathode can be prevented, it is preferred to place the contacts in thebaths so as to reduce the tendency to form the annular rings.

In the construction illustrated in Figures 16 and 17, a roller ||5 is secured to a shaft ||6 and the shaft is driven by a pulley ||1 connected to any suitable source of power. The shaft is mounted in bearings 8 and 9 disposed, respectively, inside and outside of the tronnel. The

roller 5 is disposed at an acute angle to the direction of travel oi' the core 6. Electrical connection is made with the shaft 6 by a brush |20. In order to prevent formation of nodules of copper on the contact, a scraper |2 which is pivoted as indicated by the reference numeral |22 and provided with a Weight |23, is employed. The end |24 of the scraper opposite the weight contacts with the roller and removes any copper which might otherwise adhere to it.

A great deal of diiiculty has been experienced in obtaining a good deposit of copper on the core which had previously been coated with nickel in the tronnel 1. It was found that copper displaced the nickel on the core when it passed through the copper solution in the tronnel 8. Spongy copper of poor bonding quality was thus formed. This diiiculty was nally overcome by employing a circular anode of high current density concentrically placed around the cathode rod at the entrance end of the tronnel 8. This circular anode |30 is illustrated in Figures 13 and 14. It is an insoluble anode such as lead which extends only a small part of the length of the tronnel and partially surrounds the cathode 6. It is supported by straps 3| which t over the sides of the tronnel. The use of the high current density anode counteracts the tendency of the previously deposited nickel to be displaced by copper when it is passed through the copper solution.

An anode contact is illustrated in Figure 15. The drag wire 3| which forms the anode is supported on a porcelain base |32 resting on the bottom of the tronnel which has a lead lining |33. A contact brush |34 contacts with the drag wire.

Current for carrying out the electrodeposition of the metals is supplied by a series of generators |40, 4| and |42 connected, respectively, to motors |43, |44 and |45, and a generator |10 connected to a motor 1| 'Ihe tronnels 3 and 4 are connected in series with the generator |40 by conductors |46 and |41. The negative conductor |48 of the generator 4| is connected to an iron anode |49 in the tronnel 5. The posi.-

tive conductor |50 of the generator 4| is connected in parallel to a plurality of nickel anodes |I, |52, |53, |54 and |55. The anodes |5| to |55 are connected to the'conductor |50 through 5 resistances |56, |51, |58, |59 and |60, respectively. The resistance |56 is the greatest and |60 is the least, the intermediate resistances decreasing from |56 to |60 as indicated on the drawings. This arrangement tends to produce a uniform current density throughout the length of the core wire within the tronnel 1. If varying resistances are not employed, the tendency is to have the greatest current density at the entrance end of the tronnel, which results in uneven deposition of the nickel. The varying resistances |56 to |60 counterbalance the resistance of the core wire, thereby equalizing the current densities along the whole length of the wire and causing deposition of metal throughout substantially the whole length of the tronnel.

The circular high current density anode 30 which is illustrated in detail in Figures 13 and 14 is connected by a positive conductor |65 to the generator |42. The negative conductor |66 is connected at the point |61 by a roller contact to the core wire 6. An anode |68 is connected by a positive conductor |69 to a generator |10 which is driven by a motor I1|. The drag wire 3| is connected at points |12 and |13 within the tronnels 9 by positive conductors |14 and |15, respectively. Negative conductors |16, |11 and |18 connect the generator with points |61, |19 and |80, respectively, on the cathode wire.

In order to better equalize the current density along the length of the cathode Wire in the tronnels 9, a shield is placed around the vcathode near.A the entrance end of the tronnel, as illustrated in Figures 19 and 20. A shield |85 is placed in the tronnel near the entrance end between the drag wire 3| forming the anode and the process wire 6 forming the cathode. The drag wire has a very low electrical resistance compared to the process wire, since the former is of larger diameter than the latter and also because it is copper, whereas the process wire is steel, or steel on which copper has been deposited. If a shield is not used, the current takes the path of least resistance, and, instead of owing uniformly from the anode to the cathode through the length of the tronnel, ows along the drag wire in both directions from the anode contact |86, rather than flowing through that portion of the bath near the anode contact. Under these conditions, a higher current density is obtained at the ends of the tronnels which are nearer to the cathode contacts |81 than is obtained at the middle of the tronnels. By interposing shields of non-conducting material between the anode and the cathode adjacent'the cathode contacts, that is, between the Wires 3| and 6 near the ends of the tronnels, the inequality in current density is minimized.

The greater the current density employed in the tronnels 9, the more rapid the deposition of copper will be and the less is the length of the apparatus required in order to deposit a given amount of copper. When the core wire enters the first of the tronnels in which copper is deposited thereon, it has a relatively low conductivity, the conductivity being about '1% where a steel core is employed. If it is attempted to apply too high a current density to the core wire in this tronnel, the deposit of copper is coarse and granular. I have found, however, that as the amount of copper is progressively built up due to its passage through the various tronnels, a higher average current density can be employed in each succeeding tronnel and still produce a satisfactory deposit. In carrying out the process, I, therefore, prefer to progressively increase the current density as the exit end of the apparatus is reached. This enables me to form a satisfactory deposit and still keep the number of tronnels, or the length of a single tronnel if only one is used, within commercially practical limits. The proper spacing of the cathode contacts affects both the quality of the deposit and the cost of the process. High current densities decrease the total length of tron'- nels needed to produce a deposit of a certain thickness, but the current density cannot exceed a certain amount without injuring the quality of the deposit. In order to keep the current density within the limits which will give a good deposit, I preferably increase the distance between cathode contacts in the direction of travel of the core. If separate baths are employed, the. length of the containers or tronnels 9, and the distance between cathode contacts likewise increases. The increased resistance due to the increased length of the coated core between cathode contacts compensates for the decreased resistance per unit of length resulting from the increased diameter of the coated core as the deposition continues. Important factors determining the proper spacing of cathode contacts are as follows:

(1) The area of the process wire.

(2) The conductivity of the process wire.

(3) The average current density per square foot.

(4) The electrical resistance of the solution, which resistance changes with the composition and temperature of the solution.

(5) The distance between anode and cathode.

I have established a convenient rule for determining the distance between cathode contacts. Such distance for any part of the apparatus may be determined by multiplying the then area of the process wire (expressed in square inches) by the then conductivity of the process wire (expressed in percent of the conductivity of a wire of like size but all of one metal, e. g., copper) :y a constant. I have found that the gure 100 is a good one to use as the constant in such formula and that the application of the formula gives the distance between cathode contacts in inches. 100 is, as stated, a good figure, but this may vary from 50 to 150. An example of the application of the formula is as follows:

Required, the distance between cathode contacts at the beginning of the coating operation, coating bare steel wire 1%; inch diameter. The area of the wire in square inches equals .11 approximately. 'Ihe conductivity expressed as a percentage of a copper wire is '1. Therefore, the proper distance between cathode contacts equals .ll '1 100=17 inches.

In Figures 21, 22 and 23 there is shown a preferred form of roller support for supporting the core either between tronnels or in a tronnel, the support being adapted to compact the deposited copper or other metal and rene its grain structure. In this device the core having a coating of metal thereon is supported by two rollers having their axes extending in the direction of travel of the wire. Each of these rollers is of larger diameter at its center than at its end and is of a shape such as would be formed by placing the bases of two truncated cones on each other.

, may be used in carrying out the process.

This type of roller provides a point contact for the core instead of a line contact such as would be provided by the usual cylindrical rollers. The core is supported by the large diameter portions |9| of the rollers. The rollers are preferably made of a hard corrosion resistant alloy, such as high chrome steel, or iron containing about 13% silicon, each roller being supported on a copper shaft |92. The shafts are connected to a coupling |93 which is connected at its upper end to a copper pipe |94 provided with a funnel |95. A cathode connection 196 is made with the pipe |94. Slightly acidulated water is supplied to the pipe |94, and after owing through the pipe, flows through the hollow shafts |92 of each of the rollers and is delivered through openings 91 in the pipe to the rollers and from the rollers to the core 6. The supply of acidulated water to the rollers prevents the formation of a dark colored stain in the same manner as described in connection With the embodiment shown in Figures 10 and 1l.

There is a wedging action between the core and the rollers which compacts and refines the grain of the deposited copper. This compacting action is many times as great as would be the case if ordinary cylindrical rollers were employed, since with the angular type rollers described, all of the weight of the core is concentrated at a single point on each roller. As the core revolves, the rollers form a helical path or slight groove in the copper, thereby compacting it and refining the grain structure by the mechanical work done thereon. In the illustrated embodiment, the two rollers of each supporting and compacting device are so placed that their centers are slightly out of alinement. That is, the center of one of the rollers |90 is advanced slightly beyond the center of the other roller, the advance being equal to the pitch of the path made by the rollers, so that when the core has passed over one set of rollers, only a single compacted path is formed on the copper.

A number of sets of rollers of the type described Figure 24 illustrates the paths made by two successive sets of rollers. Before the core having a coating of copper thereon has reached the rst set of rollers, it has a diameter D, as shown in Figure 24. As the coated core passes over the first set of rollers, a path |98 is formed therein, in which path the grains of copper have been rened and compacted. As further copper is deposited the diameter increases as represented by D', and when the core with the further amount of copper thereon reaches a second set of rollers, a second compacted path |99 is formed thereon. It will be seen that by increasing the number of sets of rollers, the compacting and refining action of the rollers may be exerted over substantially the entire surface of the deposited metal. The great advantage of using angular rollers instead of cylindrical rollers is that the compacting and grain refining effect is enormously increased due to the point contact between the rollers and the deposited metal, and at the same time most of the crystal nuclei have been left undisturbed. The use of supports in a system of this kind is highly advantageous as it permits of handling the wire expeditiously and without any deleterious effects upon the product. The guiding of the wire by means of the supports insures accurate positioning thereof at all times, thereby insuring that proper conditions will be maintained in the apparatus.

I prefer to use all of the different types o-f supports for the core which I have described, the different types of supports being used at different points in the process. Thus, in the tronnels, 3, 4, 5, 1 and 8, it is preferred to use solution contacts, that is, to avoid any mechanical contact with the core, as it has been found that minute scratches which are made by the use of mechanical contacts will be carried through the Whole process and the defects may actually increase as the process progresses. At the point |61 in Figure 18 between the tronnel 8 and the rst tronnel 9, it is preferred to use a power driven roller contact of the type shown in Figures 16 and 17. It is necessary to supply current at this point, and yet the deposit is delicate. The use of power driven rollers reduces the friction which would be encountered with idler rollers and, therefore, reduces the tendency to scratch or mar the deposit. In passing through the first tronnel 9 containing a hot copper solution, a relatively heavy deposit is made, so that a roller contact of the type shown in Figures 10 and 11 may be employed at the point |19. It is not necessary to use power driven rollers at this point, and yet the deposit at this point is not thick enough to advantageously use the compression rollers shown in Figures 21, 22 and 23. At point and thereafter during the process, it is preferred to use the compression rollers shown in Figures 21 to 23 to accomplish the compression and refinement in grain structure which has been described.

Anfadvantage of the present process is that it gives a wide choice of combination of metals.

Certain of the high carbon steels cannot be successfully rolled at temperatures as low as 1900 F., yet in rolling bimetallic ingots, this temperature cannot be exceeded, because to do so would melt the copper. In consequence, it has not been possible to manufacture bimetallic bodies by the molten process wherein the core steel had a high percentage of carbon.

Although it is preferred to use a steel core Wire and to deposit a coating of nickel and then a coating of copper thereon, the rst coating may be eliminated and the copper may be deposited directly upon the core wire. Other metals than steel, copper and nickel may be employed, the compositions of the various cleaning solutions and electrolytic baths may be changed, and other shapes than wire may be produced.

I have illustrated and described the present preferred embodiment and manner of practicing my invention, but it should be understood that the invention may be otherwise embodied or practiced within the scope of the following claims.

I claim:

1. In the method of electrodepositing metal on a core, the steps comprising passing the core as a cathode through an electrolytic bath, rotating the core axially while passing through the bath, and forming compacted spaced paths in the form of helixes on the deposited metal to refine the grain structure.

2. In the method of electrodepositing metal on a core, the steps comprising passing the core as a cathode through an electrolytic bath, rotating the core axially while passing through the bath, forming compacted helical paths on the deposited metal to refine the grain structure, and depositing additional metal on the compacted electrodeposited metal.

,3, The method of compacting metal which has been electrodeposited on a core, which comprises axially rotating the core having metal electrodeposited thereon, and While rotating it compacting helical grooves in the deposited metal to compact it and refine the grain structure.

4. In the method of electrodeposition of a metal on a base, the steps consisting in maintaining the base under a tension.approaching its yield point and electrodepositing metal on the tensioned base.

5. In the method of electrodeposition of a metal on a ferrous base, the steps consisting in maintaining such base under a tension of 20,000- 50,000 pounds per square inch, and electrodepositing metal on the tensioned base.

6. In the method of electrodepositing metal on a base, the steps consisting in passing the base as a cathode through an electrolytic bath to effect deposition of metal, compacting spaced zones on the deposited metal, and continuing the deposition.

7. A method of forming a Wire of the type described which comprises passing a core wire as a cathode through a solution of the metal which is to form a sheath, plating metal from said solution onto said core Wire, and rotating the Wire about its axis While passing through said solution.

8. A method of forming a wire of the type described Which comprises passing a core wire as a cathode through a solution of the metal which is to form a sheath, plating metal from said solution onto said core wire, rotating the wire about its axis while passing through said solution and burnishing said Wire.

9. A method of forming a wire. of the type described which comprises passing a core wire under tension as a cathode through an electro lytic bath to form a sheath, plating metal from said bath onto said core Wire, rotating the wire about its axis While passing through said bath and burnishing said Wire.

10. A method of forming a wire of the type described which comprises passing a core wire under tension as a cathode through an electro- Lvtic bath to form a sheath, plating metal from' said bath onto said core Wire, rotating the wire about its axis while passing through said bath, burnishing said Wire and passing said wire through a series of tanks and rotatably supporting said Wire between said tanks.

11. The method of forming a multi-metallic article, which comprises pulling an elongate core, such as a Wire, as a cathode through a solution of the metal which is to form a sheath, subjecting the core being fed to the solution to a force reacting against the pull in its direction of travel to maintain the core under tension. electrodepositing metal onto said core While under tension, and rotating the core about its axis While passing through said solution.

12. The method of forming a. Wire of the type described, which comprises advancing a core Wire as a cathode through a series of electrolytic baths in a substantially straight path against a backward tensioning pull, electrodepositing metal on said core wire, rotating the wire about its axis While passing through said baths, and supporting said Wire in its axial path while passing through said baths.

13. The method of electrodeposition, which comprises unreeling a core wire, advancing the core Wire in a substantially straight path through an electrolytic bath, reeling up the coated product after passing through the bath,

about its axis While pulling it through said solution.

15. The method of producing a multi-metallic article, which comprises advancingan elongate core in a single direction at a substantially I constant rate as a cathode through a solution of the 'metal which is to form a sheath, electrodepositing metal onto said core as a permanent sheath, and rotating the core about its axis While advancing it through said solution.

16. The method of electrolytically forming successive deposits of diierent metals on a core, which comprises passing a core as a cathode through successive metallic baths of different metals, and substantially surrounding the core as it enters a bath of a different metal from the metal of the preceding bath with an anode of such potential as to effect a sufficiently high cathodic current density to produce a light ash coat of said different metal and subsequently depositing said different metal at ordinary current densities in the remainder of the bath.

17. The method of electrodepositing metal on a core, which comprises passing the core as a cathode through successive baths of nickel and copper, and acting upon the nickel coated core as it enters the copper bath by an anode of such potential as tol eiect a suiciently high cathodic current density to produce a light flash coat of copper thereon and subsequently depositing copper thereon at ordinary current densities in theremainder of the copper bath.

18. The method of producing a multi-metallic article, which comprises electrodepositing metal as a permanent sheath on an elongate core advancing as a cathode through a solution of the metal which is to form the sheath, and simultaneously rotating' the core about its axis and substantially continuously pulling the core through said solution.

19. The method of forming a multi-metallic article of the type described, which comprises pulling an elongate core, such as a wire, as a cathode through a solution of the metal which is to form a sheath, retarding the feed of said core into the solution so as to cooperate with the pull on the core in maintaining the core under tension while in the solution, electrodepositing metal from said solution on said tensioned core, rotating the core about its axis while passing through said solution, and supporting said core While. passing through said solution.

20. The method of forming a multi-metallic article, which comprises substantially continuously advancing a core of unrestricted length such as a wire in a substantially straight path through a solution of the metal which is to form a sheath, rotating the core about its axis while passing through said solution, and electrodepositing a permanent sheath of metal on the core as a cathode as the latter advances through said solution. 

